Last week, the U.S. Air Force awarded a $35-billion contract to build 179 new tanker planes to a partnership between the European Aeronautic Defense and Space Company and U.S. defense contractor Northrop Grumman.

Chicago-based Boeing was the losing bidder on the job. Lawmakers from Washington state and Kansas, where Boeing operates manufacturing facilities, have demanded an explanation from the Pentagon.

Boeing had been expected to win the contract. The surprise choice of EADS marks the European company's entry into the U.S. defense market.

The Air Force uses airborne tankers to refuel fighter jets, bombers, and other military aircraft in mid-air.